Berms

To divert surface runoff, shovel dirt into a narrow, long, hill-shaped form as
shown.

You've just made a berm. Make sure the edges extend far enough beyond your
structure, so that the water leaving the berm and flowing freely down the hill
will miss your building. You might want to direct the water from your berm to
nourish your garden or orchard. If you decide to make a drain and a berm, put
the berm uphill of the drain.

For more information about drainage, go to the library and read up on as many
methods of drainage as you can find.